DocumentCode :
2622435
Title :
Nonconvexity of the capacity region of the multiple-access arbitrarily varying channel subject to constraints
Author :
Gubner, John A. ; Hughes, Brian L.
Author_Institution :
Dept. of Electr. & Comput. Eng., Wisconsin Univ., Madison, WI, USA
fYear :
1994
fDate :
27 Jun-1 Jul 1994
Firstpage :
53
Abstract :
The multiaccess arbitrarily varying channel (MAVC) subject to state and input constraints models a channel that is subject to jamming or unknown, time-varying uncertainties. The random-code capacity region has been characterized under two different assumptions. Under the assumption that the random encoders are statistically independent, the capacity region is completely characterized. In addition, it is shown by means of a simple erasure channel that this capacity region, 𝒞, is not always convex. To our knowledge, this is the first example of a synchronous multiple-access channel with a nonconvex capacity region. When the random encoders are permitted to be statistically dependent, the capacity region is denoted by 𝒞¯. Clearly 𝒞⊆𝒞¯. It is known that 𝒞¯ is always convex. By considering another erasure channel, it is shown that even when 𝒞 is convex, it is possible for 𝒞 to be a proper subset of 𝒞¯. In fact, the set-theoretic difference, 𝒞¯/𝒞, has a nonempty interior. Hence, permitting the codebooks to be dependent can increase the capacity region
Keywords :
channel capacity; channel coding; encoding; multi-access systems; time-varying channels; codebooks; constraints; erasure channel; input constraints; jamming; multiple-access arbitrarily varying channel; nonconvex capacity region; random encoders; random-code capacity region; state constraints; synchronous multiple-access channel; time-varying uncertainties; Helium; Jamming; Laboratories; Military computing; Power system modeling; Uncertainty;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Information Theory, 1994. Proceedings., 1994 IEEE International Symposium on
Conference_Location :
Trondheim
Print_ISBN :
0-7803-2015-8
Type :
conf
DOI :
10.1109/ISIT.1994.394917
Filename :
394917
Link To Document :
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